A307109 Number of integer solutions to x^2 + x*y + y^2 <= n excluding (0,0), divided by 2.

1, 1, 4, 5, 5, 5, 11, 11, 12, 12, 12, 15, 21, 21, 21, 22, 22, 22, 28, 28, 34, 34, 34, 34, 35, 35, 38, 44, 44, 44, 50, 50, 50, 50, 50, 51, 57, 57, 63, 63, 63, 63, 69, 69, 69, 69, 69, 72, 79, 79, 79, 85, 85, 85, 85, 85, 91, 91, 91, 91, 97, 97, 103, 104, 104, 104

Offset: 1

Author

Hugo Pfoertner, Mar 25 2019

Keywords

• nonn

Examples

			a(1)=a(2)=(2/2)=1: 2 solutions (-1,1),(1,-1);
a(3)=(8/2)=4: 2 solutions for n<3 and the 6 solutions (1,1), (-1,-1), (1,-2), (2,-1), (-1,2), (-2,1);
a(4)=a(5)=a(6)=10/2=5: 8 solutions for n<6 and the 2 solutions (-2,2), (2,-2).
		

Crossrefs

Cf. A014201, A014202, A198799, A230655, A300419.